mm: avoid unnecessary use of is_swap_pmd()

PMD 'non-swap' swap entries are currently used for PMD-level migration
entries and device private entries.

To add to the confusion in this terminology we use is_swap_pmd() in an
inconsistent way similar to how is_swap_pte() was being used - sometimes
adopting the convention that !pmd_none(), !pmd_present() implies PMD 'swap'
entry, sometimes not.

This patch handles the low-hanging fruit of cases where we can simply
substitute other predicates for is_swap_pmd().

No functional change intended.

Link: https://lkml.kernel.org/r/8a1704b36a009c18032d5bea4cb68e71448fbbe5.1762812360.git.lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Byungchul Park <byungchul@sk.com>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: Chris Li <chrisl@kernel.org>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Gregory Price <gourry@gourry.net>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jann Horn <jannh@google.com>
Cc: Janosch Frank <frankja@linux.ibm.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Joshua Hahn <joshua.hahnjy@gmail.com>
Cc: Kairui Song <kasong@tencent.com>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Leon Romanovsky <leon@kernel.org>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Mathew Brost <matthew.brost@intel.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Naoya Horiguchi <nao.horiguchi@gmail.com>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Nico Pache <npache@redhat.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Rakie Kim <rakie.kim@sk.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Wei Xu <weixugc@google.com>
Cc: xu xin <xu.xin16@zte.com.cn>
Cc: Yuanchu Xie <yuanchu@google.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

1 files changed, 28 insertions, 22 deletions

diff --git a/mm/memory.c b/mm/memory.c
index 0caf8c5c8c68..76c17feff88b 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1376,6 +1376,7 @@ copy_pmd_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma,
 		next = pmd_addr_end(addr, end);
 		if (is_swap_pmd(*src_pmd) || pmd_trans_huge(*src_pmd)) {
 			int err;
+
 			VM_BUG_ON_VMA(next-addr != HPAGE_PMD_SIZE, src_vma);
 			err = copy_huge_pmd(dst_mm, src_mm, dst_pmd, src_pmd,
 					    addr, dst_vma, src_vma);
@@ -6340,35 +6341,40 @@ retry_pud:
 	if (pmd_none(*vmf.pmd) &&
 	    thp_vma_allowable_order(vma, vm_flags, TVA_PAGEFAULT, PMD_ORDER)) {
 		ret = create_huge_pmd(&vmf);
-		if (!(ret & VM_FAULT_FALLBACK))
+		if (ret & VM_FAULT_FALLBACK)
+			goto fallback;
+		else
 			return ret;
-	} else {
-		vmf.orig_pmd = pmdp_get_lockless(vmf.pmd);
+	}
 
-		if (unlikely(is_swap_pmd(vmf.orig_pmd))) {
-			if (is_pmd_device_private_entry(vmf.orig_pmd))
-				return do_huge_pmd_device_private(&vmf);
+	vmf.orig_pmd = pmdp_get_lockless(vmf.pmd);
+	if (pmd_none(vmf.orig_pmd))
+		goto fallback;
 
-			if (is_pmd_migration_entry(vmf.orig_pmd))
-				pmd_migration_entry_wait(mm, vmf.pmd);
-			return 0;
-		}
-		if (pmd_trans_huge(vmf.orig_pmd)) {
-			if (pmd_protnone(vmf.orig_pmd) && vma_is_accessible(vma))
-				return do_huge_pmd_numa_page(&vmf);
+	if (unlikely(!pmd_present(vmf.orig_pmd))) {
+		if (is_pmd_device_private_entry(vmf.orig_pmd))
+			return do_huge_pmd_device_private(&vmf);
 
-			if ((flags & (FAULT_FLAG_WRITE|FAULT_FLAG_UNSHARE)) &&
-			    !pmd_write(vmf.orig_pmd)) {
-				ret = wp_huge_pmd(&vmf);
-				if (!(ret & VM_FAULT_FALLBACK))
-					return ret;
-			} else {
-				huge_pmd_set_accessed(&vmf);
-				return 0;
-			}
+		if (is_pmd_migration_entry(vmf.orig_pmd))
+			pmd_migration_entry_wait(mm, vmf.pmd);
+		return 0;
+	}
+	if (pmd_trans_huge(vmf.orig_pmd)) {
+		if (pmd_protnone(vmf.orig_pmd) && vma_is_accessible(vma))
+			return do_huge_pmd_numa_page(&vmf);
+
+		if ((flags & (FAULT_FLAG_WRITE|FAULT_FLAG_UNSHARE)) &&
+		    !pmd_write(vmf.orig_pmd)) {
+			ret = wp_huge_pmd(&vmf);
+			if (!(ret & VM_FAULT_FALLBACK))
+				return ret;
+		} else {
+			huge_pmd_set_accessed(&vmf);
+			return 0;
 		}
 	}
 
+fallback:
 	return handle_pte_fault(&vmf);
 }